Hydrogen stability in diamond-like carbon films during wear tests

Hydrogen stability has been investigated during wear tests in particular diamond-like carbon films deposited in a dual electron cyclotron resonance radio frequency glow discharge plasma system, at two different substrate bias voltages equal to −30 and −600 V, for series I and series II, respectively. Combined infrared absorption and elastic recoil detection analysis experiments are used to fully characterize the films in their as-deposited state and after wear tests. The results indicate clearly that the total bonded hydrogen content as well as the total hydrogen concentration decrease during wear tests for the two series. Two mechanisms are discussed to explain these results, e.g., the surface contact graphitization due to heating effect and the hydrogen diffusion to the free surface as a result of plastic deformation process.